Systems and methods for treating tissue regions of the body

ABSTRACT

Systems and methods deploy a therapeutic or diagnostic element into contact with a body tissue region. The systems and methods can sense position of the therapeutic or diagnostic element relative to a targeted tissue region without direct or indirect visualization, by sensing fluid pressure in a fluid path having an outlet located at or near the therapeutic or diagnostic element. The systems and methods can also inflate the therapeutic or diagnostic element during use, while taking steps to avoid over-inflation and/or while dynamically monitoring the pressure conditions within the expanded element.

RELATED APPLICATIONS

This application is a divisional of copending patent application Ser.No. 11/114,592 filed 26 Apr. 2005, which is a continuation of patentapplication Ser. No. 10/857,632, filed May 28, 2004, which is acontinuation-in-part of U.S. patent application Ser. No. 09/955,915,filed Sep. 19, 2001, now U.S. Pat. No. 6,699,243, which is incorporatedherein by reference.

FIELD OF THE INVENTION

The invention is directed to devices, systems and methods for treatingtissue regions of the body.

BACKGROUND OF THE INVENTION

Catheter-based devices that deploy expandable structures into interiorbody regions are well known. These structures are typically introducedthrough a body lumen or vessel in a collapsed, low profile condition.Once at or near the targeted body region, the structures are expanded insitu into an enlarged condition to make contact with tissue. Thestructures can carry operative elements that, when in contact withtissue, perform a therapeutic or diagnostic function. They can, forexample, deliver energy to ablate targeted tissue in the region.

Some of these structures can be expanded by inflation by delivery offluid into the interior of the structure. It is desirable to control theamount of inflation, so as not to over-inflate the structures.Over-inflation can lead to damage of the structure, or unintended traumaor damage to nearby tissue.

With structures that are expanded in situ, it is also desirable toascertain whether the structure actually is in contact with the targetedtissue region. Absent such contact, the desired therapeutic ordiagnostic outcome may not be achieved.

SUMMARY OF THE INVENTION

The invention provides improved systems and methods for treating atissue region.

One aspect of the invention provides systems and methods for sensing theposition of a therapeutic or diagnostic element with respect to atargeted tissue region. The systems and methods comprise a fluid pathhaving an outlet located at or near the therapeutic or diagnosticelement. The location of the outlet places the outlet into a positionwith respect to the targeted tissue region concurrently with thetherapeutic or diagnostic element. The systems and methods also includea source of fluid under pressure. The source is in communication withthe fluid path to convey fluid under pressure through the fluid path.The systems and methods include a fluid pressure sensor, whichcommunicates with the fluid path to sense prevailing fluid pressure inthe path. The systems and methods also include an output to indicate thesensed prevailing fluid pressure or changes in the sensed prevailingfluid pressure over time. The sensed pressure conditions correlate withthe position of the therapeutic or diagnostic element relative to thetargeted tissue region. In one embodiment, the source of fluid conveysair under pressure, and the fluid pressure sensor comprises a manometer.

According to this aspect of the invention, changes in tissue pressure ator near the path outlet governs fluid flow in the path and gives rise tochanges in fluid pressure within the path. Changes in the prevailingfluid pressure can be correlated to the position of the path outletrelative to a targeted tissue region. This aspect of the invention makespossible the sensing of the position of a remote structure with respectto a targeted tissue region without direct or indirect visualization, orwithout other complicated electrical or mechanical paraphernalia.

Another aspect of the invention provides systems and methods forinflating an inflatable structure that carries a therapeutic ordiagnostic element. The systems and methods comprise a source of fluidunder pressure. A supply line communicates with the inflatable structureand the source to convey fluid into the inflatable structure to inflatethe inflatable structure for use. The systems and methods include apressure relief valve. The pressure relief valve communicates with thesupply line. The pressure relief valve opens and vents fluid from thesupply line when a predetermined pressure condition exists in the supplyline. This pressure condition is indicative that a desired interiorpressure exists within the inflatable structure. This aspect of theinvention assures that the inflatable structure is not subject toover-inflation during use.

Another aspect of the invention provides systems and methods fordynamically monitoring pressure conditions within an inflatablestructure that carries a therapeutic or diagnostic element. The systemsand methods include a pressure sensing element that dynamically sensesinterior pressure within the inflatable structure and generates anoutput. The sensing can be accomplished in real time, with anappropriate output generated to provide visual or audible feedback tothe operator, and/or provide automated process control feedback basedupon the sensed pressure information. The use of a dynamic pressuresensing element makes possible the automated inflation of an inflatablebody in a straightforward and reliable manner. The use of dynamicpressure monitoring and control also facilitates the use of a porousballoon structure. The porous balloon structure is inflated to a desiredpressure condition by the delivery of a liquid, while a portion of theinflation liquid is discharged through pores in the balloon, to providea desired flow of irrigation fluid to the tissue region concurrent withinflation.

Other features and advantages of the inventions are set forth in thefollowing Description and drawings, as well as in the appended claims

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a system for treating tissue.

FIG. 2 is an enlarged view of the treatment device, with parts brokenaway and in section, that is associated with the system shown in FIG. 1,the treatment device comprising basket structure that carriesselectively deployable electrode elements and that expands in responseto inflation of an interior balloon structure, FIG. 2 showing the basketin a collapsed condition with the electrode elements retracted.

FIG. 3 is an enlarged view of the treatment device shown in FIG. 2, withthe basket expanded due to inflation of interior balloon structure andthe electrode elements still retracted.

FIG. 4 is an enlarged view of the treatment device shown in FIG. 2, withthe basket expanded due to inflation of interior balloon structure andthe electrode elements extended for use, FIG. 4 also showing the passageof irrigation fluid from the basket to cool the surface tissue whileradio-frequency energy is applied by the electrode elements tosubsurface tissue.

FIGS. 5 to 7 are simplified anatomic views showing the use of thetreatment device shown in FIGS. 2 to 4 deployed in the region of thelower esophageal sphincter to form an array of lesions.

FIGS. 8 and 9 show, in simplified anatomic and schematic views, a systemand method for sensing the position of the treatment device shown FIGS.2 to 4 with respect to a targeted tissue region, by sensing fluidpressure in a fluid path having an outlet located at or near theelectrode elements.

FIGS. 10 to 13 show, in perspective views, a system and method formanually inflating the balloon structure in the treatment device shownin FIGS. 2 to 4 while tactilely monitoring the magnitude of theinflation pressure to avoid over-inflation of the balloon structure.

FIGS. 14 and 15 show, in perspective views, a system and method formanually inflating the balloon structure in the treatment device shownin FIGS. 2 to 4 while using a pressure relief valve to avoidover-inflation of the balloon structure.

FIG. 16 shows, in a perspective view, a system and method that inflatethe balloon structure in the treatment device shown in FIGS. 2 to 4,while dynamically monitoring pressure conditions within the balloonstructure in real time, with an appropriate output generated to providevisual or audible feedback to the operator, and/or provide automatedprocess control feedback based upon the sensed pressure information.

FIG. 17 shows, in a perspective view, a system and method thatautomatically inflate the balloon structure in the treatment deviceshown in FIGS. 2 to 4 by dynamically monitoring pressure conditionswithin the balloon structure.

FIG. 18 is a perspective view of a treatment device comprising basketstructure that carries selectively deployable electrode elements andthat expands in response to inflation of an interior balloon structurewith a liquid under the control of the system shown in FIG. 17, FIG. 18showing the basket in an inflated condition with the electrode elementsextended and the inflation liquid also serving as irrigation fluiddischarged through an array of openings formed in the balloon structure.

The invention may be embodied in several forms without departing fromits spirit or essential characteristics. The scope of the invention isdefined in the appended claims, rather than in the specific descriptionpreceding them. All embodiments that fall within the meaning and rangeof equivalency of the claims are therefore intended to be embraced bythe claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This Specification discloses various catheter-based systems and methodsfor treating dysfunction in various locations in an animal body. Forexample, the various aspects of the invention have application inprocedures requiring treatment of sphincters and adjoining tissueregions in the body, or hemorrhoids, or incontinence, or obesity, orrestoring compliance to or otherwise tightening interior tissue ormuscle regions. The systems and methods that embody features of theinvention are also adaptable for use with systems and surgicaltechniques that are not necessarily catheter-based.

The systems and methods are particularly well suited for treatingdysfunctions in the upper gastrointestinal tract, e.g., in the loweresophageal sphincter and adjacent cardia of the stomach. For thisreason, the systems and methods will be described in this context.Still, it should be appreciated that the disclosed systems and methodsare applicable for use in treating other dysfunctions elsewhere in thebody, which are not necessarily sphincter-related.

I. Overview

A tissue treatment device 10 and associated system 36 are shown in FIG.1.

The device 10 includes a handle 12 made, e.g., from molded plastic. Thehandle 12 carries a flexible catheter tube 14 constructed, for example,by extrusion using standard flexible, medical grade plastic materials,like Pebax™ plastic material, vinyl, nylon, poly(ethylene), ionomer,poly(urethane), poly(amide), and poly(ethylene terephthalate). Thehandle 12 is sized to be conveniently held by a physician, to introducethe catheter tube 14 into the tissue region targeted for treatment. Thecatheter tube 14 may be deployed with or without the use of a guidewire.

The catheter tube 14 carries on its distal end an operative element 16.The operative element 16 can take different forms and can be used foreither therapeutic purposes, or diagnostic purposes, or both. Theoperative element 16 can support, for example, a device for imaging bodytissue, such as an endoscope, or an ultrasound transducer. The operativeelement 16 can also support a device to deliver a drug or therapeuticmaterial to body tissue. The operative element 16 can also support adevice for sensing a physiological characteristic in tissue, such aselectrical activity, or for transmitting energy to stimulate tissue orto form lesions in tissue.

In the embodiment shown in FIGS. 2 to 4, the operative element 16comprises a three-dimensional basket 18. The basket 18 includes an arrayof arms 20. The arms 20 are desirably made from extruded or moldedplastic, but they could also be formed from stainless steel or nickeltitanium alloy. As shown in FIG. 2, the arms 20 are assembled togetherbetween a distal tip 22 and a proximal base element 24.

As FIGS. 3 and 4 show, an expandable structure 26 comprising, e.g., aballoon, is located within the basket 18. The expandable balloonstructure 26 can be made, e.g., from a Polyethylene Terephthalate (PET)material, or a polyamide (non-compliant) material, or a radiationcross-linked polyethylene (semi-compliant) material, or a latexmaterial, or a silicone material, or a C-Flex (highly compliant)material. Non-compliant materials offer the advantages of a predictablesize and pressure feedback when inflated in contact with tissue.Compliant materials offer the advantages of variable sizes and shapeconformance to adjacent tissue geometries.

The balloon structure 26 presents a normally, generally collapsedcondition, as FIG. 2 shows. In this condition, the basket 18 is alsonormally collapsed about the balloon structure 26, presenting a lowprofile for deployment into the targeted tissue region.

Expansion of the balloon structure 26, e.g., by the introduction of airthrough a syringe 32 coupled to a one-way check valve fitting 42 on thehandle 12 (see FIG. 3), urges the arms 20 of the basket 18 to open andexpand, as FIG. 3 shows. The force exerted by the balloon structure 26upon the basket arms 20, when expanded, is sufficient to exert anopening force upon the tissue surrounding the basket 18.

For the purpose of illustration (see FIGS. 5 and 6), the targeted tissueregion comprises the lower esophageal sphincter (LES) and cardia of thestomach. When deployed in this or any sphincter region, the openingforce exerted by the balloon structure 26 serves to dilate the sphincterregion, as FIG. 6 shows.

Each basket arm 20 carries an electrode element 28. A push-pull lever 30on the handle (see FIG. 4) is mechanically coupled through the cathetertube 14 to the electrode elements 28. In use, pushing and pulling on thelever 30 causes the electrode elements 28 to slide within the lumens inthe basket arms 20 between a retracted position (shown in the FIG. 3)and an extended position (shown in FIG. 4). As FIG. 4 shows, theelectrode element 28, when extended, projects through an opening 56 inthe basket arm. When deployed in the tissue region (see FIG. 6), theextended electrode element 28 pierces tissue. As FIG. 4 shows,temperature sensing elements 82 (e.g., thermocouples) are desirablycarried by the arms 20 near the electrode elements 28 to sense tissuetemperature conditions.

In a desired arrangement, the electrode elements 28 deliver radiofrequency energy, e.g., energy having a frequency in the range of about400 kHz to about 10 mHz. A return path is established, e.g., by anexternal patch electrode, also called an indifferent electrode. In thisarrangement, the application of radio frequency energy serves toohmically heat tissue in the vicinity of the electrode elements 28, tothermally injure the tissue and form the localized sub-surface lesions164, which are shown in FIG. 6. Of course, tissue heating can beaccomplished by other means, e.g., by coherent or incoherent light;heated or cooled fluid; resistive heating; microwave; ultrasound; atissue heating fluid; or cryogenic fluid.

In this arrangement, the natural healing of subsurface lesions orpattern of subsurface lesions created by the applied energy leads to aphysical tightening of the sphincter and/or adjoining cardia and/or areduction in the compliance of these tissues. The subsurface lesions canalso result in the interruption of aberrant electrical pathways that maycause spontaneous sphincter relaxation. In any event, the treatment canrestore normal closure function to the sphincter.

The electrode elements 28 can be formed from various energy transmittingmaterials. For deployment in the esophagus or cardia of the stomach, theelectrode elements 28 are formed, e.g., from nickel titanium. Theelectrode elements 28 can also be formed from stainless steel, e.g., 304stainless steel, or a combination of nickel titanium and stainlesssteel.

In this arrangement, the electrode element 28 may comprise a hybrid ofmaterials comprising stainless steel for the proximal portion and nickeltitanium alloy for the distal portion.

The exterior surface of each electrode element 28 can carry anelectrical insulating material, except at its distal region, where theradio frequency energy is applied to tissue. The presence of theinsulating material serves to preserve and protect the mucosal tissuesurface from exposure to the radio frequency energy, and, thus, fromthermal damage. The insulating material can comprise, e.g., aPolyethylene Terephthalate (PET) material, or a polyimide or polyamidematerial.

As FIG. 1 shows, the treatment device 10 desirably operates as part of asystem 36. The system 36 includes a generator 38 to supply the treatmentenergy to the operative element 16. In the illustrated embodiment, thegenerator 38 supplies radio frequency energy to the electrodes 28. Acable 40 plugged into the handle 12 electrically couples the electrodeelements 28 to the generator 38. Electrode supply wires pass through thecatheter tube 14 from the handle to the electrode elements 28.

The system 36 can also include certain auxiliary processing equipment.In the illustrated embodiment, the processing equipment comprises anexternal fluid delivery or irrigation apparatus 44. In the illustratedembodiment, the fluid delivery apparatus 44 comprises an integrated,self priming peristaltic pump rotor that is carried on a side panel ofthe generator 38. Other types of non-invasive pumping mechanisms can beused, e.g., a syringe pump, a shuttle pump, or a diaphragm pump.

A luer fitting 48 on the handle 12 couples to tubing 34 to connect thetreatment device 10 to the fluid delivery apparatus 44. Irrigationsupply tubing in the catheter tube 14 conveys irrigation fluid through alumen in each basket arm 20 for discharge through irrigation openings 56(see FIG. 4) by or near the electrode elements 28. This provideslocalized cooling of surface tissue. In the illustrated embodiment, theirrigation fluid (designated F in FIG. 4) is discharged directly at thebase of each electrode element 28. In this arrangement, the irrigationfluid is conveyed through the same basket arm lumen and is dischargedthrough the same basket arm opening 56 as the electrode element 28. Ofcourse, other irrigation paths can be used.

In this arrangement, the processing equipment desirably includes anaspiration source 46. Another luer fitting 50 on the handle 12 couplestubing to connect the treatment device 10 to the aspiration source 46.The aspiration source 46 draws irrigation fluid discharged by or nearthe electrodes 28 away from the tissue region. The aspiration source 46can comprise, for example, a vacuum source, which is typically presentin a physician's suite.

The system 36 also desirably includes a controller 52. The controller 52is linked to the generator 38 and the fluid delivery apparatus 44. Thecontroller 52, which preferably includes an onboard central processingunit, governs the power levels, cycles, and duration that the radiofrequency energy is distributed to the electrodes 28, to achieve andmaintain temperature levels appropriate to achieve the desired treatmentobjectives. In tandem, the controller 52 also desirably governs thedelivery of irrigation fluid.

The controller 52 desirably includes an input/output (I/O) device 54.The I/O device 54, which can employ a graphical user interface, allowsthe physician to input control and processing variables, to enable thecontroller to generate appropriate command signals.

In use (see FIGS. 5 to 7), the operative element 16 can be deployed ator near the lower esophageal sphincter (LES) for the purpose of treatingGERD. A physician can use the visualization functions of, e.g., anendoscope to obtain proper position and alignment of the operativeelement 16 with the LES.

Once proper position and alignment are achieved (see FIG. 6), thephysician can expand the balloon structure 16 and extend the electrodeelements 16 into piercing contact with tissue at or near the LES.Application of ablation energy forms the lesions 164. Retraction of theelectrode elements 28 and collapsing of the balloon structure 16 allowsthe physician to reposition the operative element 16 and perform one ormore additional ablation sequences (see FIG. 7). In this way, thephysician forms a desired pattern of circumferentially and axiallyspaced lesions 164 at or near the LES and cardia.

II. Positioning Based Upon Fluid Pressure Sensing

It is desirable to be able to confirm that the basket arms 20 arepositioned at or near the targeted tissue region. Direct visualizationcan be used for this purpose. In addition, or alternatively, electrodeimpedance can also be electrically sensed by the controller 52. Areduction in electrode impedance reflects that the electrode element 28rests in tissue, compared to when the electrode element 28 is not incontact with tissue.

Alternatively, or in combination, the system 36 can include means 58 forassessing position based upon sensed changes in tissue pressure in andsurrounding a targeted tissue region. The changes in tissue pressure aresensed based upon changes in pressure of a fluid (e.g., air or liquid)that is conveyed at or near the surface of the operative element 16where tissue contact is intended. The means 58 includes means forcausing a fluid subject to a pressure to flow in a path that has anoutlet located at or near a surface of the operative element 16 intendedto make tissue contact. Tissue pressure encountered at or near the pathoutlet affects pressure exerted on the path outlet and governs fluidflow in the path to varying degrees. The correlation between increasesin tissue pressure encountered at or near the path outlet and fluid flowthrough the path gives rise to increases in fluid pressure within thepath. The means 58 includes means for sensing a fluid pressure in thepath. An increase in the prevailing fluid pressure sensed over timecorrelates with the presence of higher tissue pressures at or near thepath outlet. The means 58 makes possible the sensing of the location ofa remote structure relative to a targeted tissue region without director indirect visualization, or without other complicated electrical ormechanical paraphernalia.

In the illustrated embodiment, the high pressure zone created by thelower esophageal sphincter is a marker for the targeted tissue region.By sensing the pressure at which fluid is delivered at a slow ratethrough ports on the basket arms 20 while moving the basket structure 18through the esophagus, the increased tissue pressure in the highpressure zone can be detected as the ports move through the zone.

In the illustrated embodiment (see FIG. 1) the means 58 includes apressurized source 60 of air and a manometer 62. The air source 60 andmanometer 62 can be part of the controller 52, or separate componentscoupled to the system 36, as FIG. 1 shows. Of course, the source 60 canprovide a fluid other than air, in which case the manometer 62 wouldcomprise a device that would sense the prevailing pressure of theselected fluid.

As shown in FIG. 1, the air source 60 and manometer 62 are coupled bytubing 64 to the irrigation supply tubing 34, which leads to the device10. An inline valve 66 controls communication between the air source 60and the tubing 34. When the valve 66 is opened, pressurized air from thesource 60 is conveyed through the irrigation lumens in the basket arms20, where they exit through the outlets 56. The flow of pressurized airthrough this path does not occur when the valve 66 is closed. In thisway, pressurized air can be selectively conveyed through the lumen orlumens when it is desired to assess the location of the basket structure18 relative to the high pressure zone of the lower esophageal sphincter.The manometer 62 senses the air pressure prevailing in the air path 64and provides an output reflecting the magnitude of the sensed pressure.

In use (see FIG. 8), the basket structure 18 is advanced while in acollapsed condition to a location beyond the targeted high tissuepressure zone, which in the illustrated embodiment, is the LES. Whilethe basket structure 18 remains in a collapsed condition, the valve 66is opened to place the pressurized air source 60 into communication withthe irrigation lumens in the basket arms 20. Pressurized air is conveyedthrough the lumens, exiting through the openings 56. The manometer 62will register a prevailing line pressure.

With the flow of air established, and with the basket structure 18 stillcollapsed, the physician draws the basket structure 18 back (see FIG.9). The region of the basket structure 18 where the electrodes 28 arecarried will eventually be brought into the high pressure zone. Theincreased tissue pressure in this region will impede air flow throughthe outlet openings 56 and generating a backpressure in the air path 64.As FIG. 9 shows, the manometer 62 will register an increase in sensedpressure. As the physician continues to draw the basket structure 18back, above the high pressure zone, the sensed pressure will decreaseaccordingly. The localized increase in sensed pressure can thus bepin-pointed, which indicates that the electrode region of basketstructure 18 is in the high tissue pressure zone and thereby positionedfor use. The physician turns the valve 66 off.

Using reference marks on the catheter tube 14, the high pressure zonecan be marked relative to an external anatomic reference, such as a biteblock worn by the patient. Since the outlet ports 56 are coincident withthe needle electrode locations, the exact location for delivery ofradiofrequency energy is located in this way, without the need forendoscopy (or as an adjunct to endoscopy). The physician expands thebasket structure 18 and proceeds with the lesion formation sequence.

The controller 52 can communicate with the manometer 62 (as shown inphantom lines in FIG. 1). In this arrangement, the controller 52 can bepre-programmed, e.g., to dynamically display the sensed pressure on theGUI 54 and/or to generate a visual and/or audible output when athreshold pressure indicative of tissue contact is sensed.

It should be appreciated that the manometer 62 and air pressure source60 could, alternatively, be coupled to the aspiration supply line. Stillalternatively, the manometer 62 can be carried on board the treatmentdevice 10 itself, e.g., in the handle 20.

III. Controlling Pressure in the Balloon Structure

It is desirable to establish some control mechanism to assure that theballoon structure 26 is not over-inflated or otherwise subject toover-pressure conditions. This avoids damage to the balloon structure26, as well as potential injury or trauma to tissue near or in contactwith the balloon structure 26.

A. Tactile Control

In one embodiment (see FIGS. 10 to 13), tactile feedback can be used. Inthis arrangement, a syringe 32 pre-filled with a pre-established volumeof air (e.g., 25 cc) (see FIG. 10) is coupled to the one way check valve42 on the handle. The physician depresses the plunger 50 of the syringe32 to introduce air from the syringe 32 onto the balloon structure 26.The pre-filled volume of air in the syringe 32 is empirically selectedbased upon the size and physical properties of the balloon structure 26.As the balloon structure 26 approaches its desired interior pressure,the physician will tactilely feel progressive resistance to advancementof the plunger 50. When the balloon structure 26 is at the desiredinterior pressure, releasing the plunger will allow a finite back flowvolume of air from the balloon structure 26 into the syringe 32 (e.g.,3-4 cc) (see FIG. 11). As FIG. 11 shows, the push back volume displacesthe plunger 50 by a finite amount, providing the physician with directvisual and tactile feedback that the balloon structure 26 has beenproperly inflated. When plunger push back is observed, the physicianresponds by advancing the plunger 50 to replace the push back volume (asFIG. 12 shows), placing the balloon structure 26 at its desiredinflation pressure. The physician disconnects the syringe 32 from theone-way check valve 42 (as FIG. 13 shows), which thereafter maintainsthe desired interior pressure in the balloon structure 26.

B. Pressure Relief Valve

In another embodiment (see FIG. 14), a pressure relief valve 68 may becoupled in line with the syringe 32 to the one-way valve fitting 42. Thevalve 68 is condition to open and vent the inflation fluid (in thiscase, air) at a predetermined pressure, which is selected to be thedesired interior pressure of the balloon structure 26.

In this arrangement, the relief valve 68 remains closed as the syringe32—pre-filled with a pre-established volume of air as alreadydescribed—is manipulated to convey air into the balloon structure 26,until the balloon structure 26 reaches the predetermined desiredinterior pressure. At this time (see FIG. 15), the relief valve 68 willopen, releasing excess air and venting additional air delivery by thesyringe 32. In this way, further increase in interior pressure withinthe balloon structure 26 is actively prevented.

The relief valve 68 can be located within the handle 12 or otherwisecarried by the device 10. Alternatively, the relief valve 68 can belocated in or on the supply line, as FIG. 14 shows. Still alternatively,the relief valve can be an integrated part of the controller 52, coupledby a sensing line to the device 10.

C. Real Time Pressure Monitoring

It may be desirable to dynamically monitor the magnitude of pressurewithin the balloon structure 26. For example, different pressuremagnitudes may be desired at different locations in the tissue regionwhere the pattern of lesions 164 is formed. In this embodiment, thesystem 36 includes means 70 for dynamically sensing the magnitude ofpressure within the balloon structure 26.

In the illustrated embodiment (see FIG. 16), the means 70 comprises apressure transducer 70. The pressure transducer 70 can be carried in thehandle 20 of the treatment device 10 (as FIG. 16 shows), or it can beintegrated into the controller 38.

As FIG. 16 shows, a pressure gauge coupled to the transducer (or avirtual gauge on the GUI 54, which FIG. 16 shows) can be used to displaythe sensed pressure in real time. The controller 52 can be programmed toimpose maximum pressure limits and generate visual or audible alarmconditions based upon the sensed pressure.

With dynamic monitoring of pressure, the inflation of the balloonstructure 26 can be placed under the control of the controller 52, andthereby automated. As FIG. 17 shows, the system includes a source 72 offluid pressure, which can be air or a liquid like saline. The source 72is coupled to the controller 52 and can be commanded to selectivelysupply inflation fluid under either positive or negative pressure. Thesource 72 is coupled via a supply line 74 to a supply fitting 80 on thehandle 12. This arrangement replaces the use of a manual syringe and theone-way check valve 42.

The supply line 74 includes a control valve 78, which is coupled to thecontroller 52. The supply line 74 also includes a pressure relief valve76, which is likewise coupled to the controller 52.

In use, upon positioning of the balloon structure 26 in a collapsedcondition at or near the targeted tissue site, the controller 52 (e.g.,in response to a foot switch operated by the physician) commands openingof the control valve 78. The controller 52 also commands the supply ofthe inflation fluid from the source 72 under positive pressure. Theballoon structure 26 undergoes inflation.

The transducer 70 dynamically monitors the interior pressure as theballoon structure 26 inflates. The controller 52 compares the sensedpressure to a maximum threshold, which can be either preprogrammed inthe controller 52 or based upon a selected input by the physician. Thecontroller 52 can also be programmed to select the threshold pressureaccording to the current location of the balloon structure 26, which canbe provided by input from the physician. When the sensed pressurereaches the selected maximum threshold, the controller 52 opens thepressure relief valve 76. Thereafter, the controller 52 toggles thepressure relief valve 76 open and closed to automatically maintain thedesired interior inflation pressure at the threshold.

When it is desired to change the location of the balloon structure 26,or to withdraw the balloon structure 26, the controller 52 (e.g., inresponse to a foot switch operated by the physician) commands drawingnegative pressure through the supply line 74 (while also closing therelief valve 76), to deflate the balloon structure 26. If, afterrepositioning, subsequent lesion formation is desired, the controller 52(e.g., in response to a foot switch operated by the physician) can againcommand the supply of inflation fluid under positive pressure from thesource 72, to again inflate the balloon structure 26 under the controlof the transducer 70, as just described.

In this way, the system 36 serves to automatically control the inflationand deflation of the balloon structure 26, while keeping the balloonpressure within the prescribed limits.

The system 36 is particularly well suited for use in association with anoperative element 18 as shown in FIG. 18. In this embodiment, theinflation fluid is a liquid that also serves as an irrigation fluid F.The irrigation fluid F is discharged in the vicinity of each electrodeelement 28 through an array of openings 90 formed in the balloonstructure 18 itself. The openings 90 can be formed, e.g., by laserdrilling, mechanical drilling, or poking with a hot needle. Thisarrangement eliminates the need for a dedicated irrigation passage andthrough openings in the basket arms 20. The inflation fluid therebyserves a dual purpose. First, the inflation fluid expands the basketstructure 26 carrying the electrode elements 28, enabling their use.Second, the inflation fluid also serves as an irrigation fluid to coolthe targeted tissue region. In this arrangement, the system 36 providesdynamic pressure monitoring and control of the inflation fluid andirrigation fluid, so that the requirements of simultaneous inflation ofthe balloon structure 18 and irrigation fluid delivery can be balanced,in order to inflate the balloon structure 18 to the desired pressurewhile achieving a desired irrigation fluid flow rate.

The foregoing is considered as illustrative only of the principles ofthe invention. Furthermore, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed. While the preferred embodiment has been described, thedetails may be changed without departing from the invention, which isdefined by the claims.

1. A system for sensing position of a therapeutic or diagnostic elementrelative to a body tissue region comprising a fluid path having anoutlet located at or near the therapeutic or diagnostic element andbeing positioned relative to tissue concurrently with the therapeutic ordiagnostic element, a source of fluid under pressure communication withthe fluid path to convey fluid under pressure through the fluid path, afluid pressure sensor communicating with the fluid path to senseprevailing fluid pressure, and an output to indicate the sensedprevailing fluid pressure or changes in the sensed prevailing fluidpressure over time.
 2. A system according to claim 1, wherein the sourceof fluid conveys air under pressure, and wherein the fluid pressuresensor comprises a manometer.
 3. A method for sensing position of atherapeutic or diagnostic element using the system defined in claim 1.4. A system for inflating an inflatable structure that carries atherapeutic or diagnostic element comprising a source of fluid underpressure, a supply line communicating with the inflatable structure andthe source to convey fluid into the inflatable structure to inflate theinflatable structure for use, and a pressure relief valve communicatingwith the supply line that opens and vents fluid from the supply linewhen a predetermined pressure condition exists in the supply lineindicative of a desired interior pressure within the inflatablestructure.
 5. A method for inflating an inflatable structure thatcarries a therapeutic or diagnostic element using the system defined inclaim
 4. 6. A system comprising an elongated body sized and configuredfor deployment into a targeted tissue region, an inflatable structurecarried by the elongated body, a therapeutic or diagnostic elementcarried by the inflatable structure, and a pressure sensing device thatsenses interior pressure within the inflatable structure and generatesan output.
 7. A system according to claim 6, further including acontroller coupled to the pressure sensing device to process the output.8. A method comprising providing a system as defined in claim 6, andperforming a therapeutic or diagnostic procedure using the system.
 9. Asystem comprising an elongated body sized and configured for deploymentinto a targeted tissue region, an inflatable structure carried by theelongated body, the inflatable structure including a porous region,therapeutic or diagnostic element carried by the inflatable structure, asource of inflating liquid coupled to the inflatable structure toinflate the structure while a portion of the inflating liquid isconveyed through the porous region to irrigate tissue, and a pressuresensing device that senses interior pressure within the inflatablestructure and generates an output.
 10. A device according to claim 9,further including a controller coupled to the pressure sensing device toprocess the output.
 11. A method comprising providing a system asdefined in claim 9, and performing a therapeutic or diagnostic procedureusing the system.